Back Story: The Layout is HO, the location is central Wisconsin, time period 1932 - 1955. Traction and Steam are the featured motive power. Single track with passing sidings and one branch line. Three interchanges. Towns are (from S to N) Portage(interchange w/Milw), Westfield/Endeavor, Montello(branch line from W/E), Coloma, Hancock/Plainfield, Bancroft (interchange w/CN&W) and Plover/Stevens Point (interchange w/GB&W & Soo).
I have one interlocking tower at Bancroft, Signals at P/SP & Portage. 3 through trains daily, plus local traffic to stations. Where would you put signals? I suspect the W/E to Montello should be signalled at both ends, but anything else?
I predict someone will ask for a diagram---lol. I may not follow your verbage well, but I would say to put signals wherever you need control. Since that's what prototypes do--your prototype and period would have had a signal/control standards book to be more specific. You can have signals that aren't functioning, but for appearance alone. I would expect them at all interchanges.
Richard
A track plan.... Oh you mean that amorphus shape that shifts back and forth everytime I look at the space?
I know what I want, and vaguely how I want it, but with the current basement clutter, even getting to track planning has been difficult.
The question is WHAT kind of signals are you going to use.
Automatic block signals operate sequentially informing you how far away the train (moving in the same direction as you) is from you.
Home, or Interlocking signals are controlled by the tower. They would be protecting the interlocking plant and little more.
An intelocking plant consists of the physical track plant with its tracks and signals, and the tower with its interlocking machine and model board.
In days of old (ec etc) "Armstrtong" interlocking plants were used Actually the ones in this country were mostly made by US&S (United Switch and Signal).
In this sort of a tower there are the levers, the interlocking bed (below) and pipes that connect the pevers to the device (switch points or signal) that the lever controls. Two levers (three operations) are required to move a set of swtich points. First you must move a lever to unlock the switch, then you must move the switch points, and then you must lock them again. Each movement is protected by the interlocking bed so that levers must be moved in the proper order, and so that no conflicting alignment can occur. Only when the plant is fully alligned for a movement can the signal itself be cleared to allow a train to enter the plant. If single track lines are entering the plant the departure signal (lever) must agree with the arrival leaver of the next plant down the line. Thus there will be no conflicting movements on that track.
Here is the interlocking bed below the floor of a tower similar to the one above.
Below is the more modern (actually this is an old GRS (General Railway Signal Co.) model-2 interlocking plant at the Lasalle Street Station. Notice that the front covers have been removed and the interlocking bed is clearly seen.
On this kind of a plant, electricity (or air pressure in the case of US&S machines) moves the switch points and signal heads. Only one lever is needed to move a set of switch points, but there are certain steps that most occur for this ti happen. First you pull on the lever, if it will not move, it is locked by some other lever. When it does move, it moves only half way, It locks the plant against movements conflicting with the new position of the lever, and it commands the switch machine to move the switch points. When the points have moved and locked a new signal is sent back to the machine allowing the lever to finish its movement and also relases other levers that are no longer in conflict with this alignment.
Here is a small GRS model-5 machine at the Court Street Station in Brooklyn (The Transit Museum).
And here is the INTERLOCKING MACHINE of the LION and interpretation of a GRS Model-5 machine.
NOW that you know what the machine is and what it does, you can figure out where the interlocking signals are to be placed. They protect the APPROACHES to the interlocking plant, and can protect routes within the plant, as well as the exit route if that route agrees with the levers of the tower that will be receiving the train.
Interlocking signals are controlled by the machine and by the tower operator.
In between these, out on the railroad, Automatic Block Signals keep trains from running into the back of the train ahead of them. Those can be placed wherever they are needed. On western railroads they can be several miles apart on the NYCT they can be as close together as 300' The closer they are together the more trains you can send down that track. Of course the system bets more and more expensive with each signal that you add.
Here is the relay board for the Route of the Broadway LION. These relays control the signals that keep the trains apart from each other on my railroad. But because of the cost factors cited above, I only have one block for each station platform edge. So I have several signals in a row, so that the ROW looks proper, but they act in unison between the stations because I cannot affor another 300 relays and the wiring that goes with them.
Do NOT ask the LION what time it is or he will explain the history of time and clocks and elaborate on the construction of a clock.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Trynn,
My layout is similar - An interlocking at a crossing has the usual 'absolute' signals and there are two sidings that just have ABS signals at the siding switches. Everything automatic, as the diamond is just for show. I have 8 blocks of ABS....
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Thank everyone for your replies.
I think maybe I asked the right and wrong question at the same time. Broadway they are all Armstrong Interlocking Towers. Which mean that Portage and Plover/Stevens Point are covered. Bancroft is a crossing with a Y to and from C&NW line leading not onto my main but a small interchange yard (2 tracks 7 cars each + main) so also probably an interlocking tower.
As for the rest of the signalling, I am wondering whether it would be cost effective to install semiphores at each station or just use the interlocking points and Westfield/Endeavor as section breakpoints.
I do know for operations that when the 3 through trains are enroute, All trains in the preceeding section MUST clear the main. The through trains are too long for any of the sidings to handle, so the locals have to make a run for the sidings (it should make operations interesting...as two are high speed Milk runs.)
Are you installing CTC or ABS? The stations have nothing to do with signals, its the sidings and points where trains meet or pass or where trains enter or clear the main track.
Dave H. Painted side goes up. My website : wnbranch.com
Manual Block
Manual Block? NOW you are getting complicated. A manual block generally has no signals at all. A batton, flag, or token is required to authorize occupancy of the track.
In Hong Kong (back in the '60s) I watched an operation where the engineer had to have a special batton, unique to that section of track, before he could proceed. when he got to the end of that section of track, he handed it off to the train that was waiting to proceed in the opposite direction.
On British railroads, this was far more complicated, as there could be several tokens for each section of track. Thus several trains could follow one and other in a west bound direction, but before an east bound train could be given a token all of the outstanding west bound tokens had to be accounted for in the machine before it would release an eastbound token.
Of course if you want a simple signal, manually operated, such as for train orders or at a crossing with another railroad that is a simple matter.
If you have manual switch points, you will likely enough have no signals anyway.
But as you may guess, the LION is very fond of signals and of the interlocking plant. Here is a simple typical interlocking plant:
Here are the levers that control it.
The Red levers control the signals, the black levers control the switch points. Levers in the down position places all devices in their NORMAL position. (for signals that is RED). A lever in the up position puts the device in the REVERSE position.
The red levers on the left control the signals for all movements from left to right through the entire plant.
The red levers on the right control the signals for all movements from right to left through the entire plant.
The black levers control the switch points from left to right as represented on the model board.
It is normal to return all levers to the normal position after the passage of a train. My failure to do so has resulted in some rear-end collisions at my 242nd Street terminal. I will refine my interlocking plant so that a train cannot depart the Botanic Garden station unless Lever 3 is in the NORMAL position. (That means a home signal at that station). A train cannot leave the Dyckman Street station unless Lever 3 is in the REVERSE position, clearing the home signal at that station. I will install train detectors on the terminal tracks so that the track selected by Lever 1 must be empty before Lever 3 can be cleared. Well, *that* is what interlocking plants do.
Once you know what the plant is doing, you will know where to put your signals.
Here is a link with some information that may help you get started. It may have more information than you really need but should be a good starting point for planning your signals.
http://waynes-trains.com/site/Signals/GettingStarted/SignalsGettingStarted1.html
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.